1. Field of the Invention
The present invention relates to a swing device, more particularly to a swing device with a driving unit for swinging a seat member.
2. Description of the Related Art
FIGS. 1 to 4 illustrate a conventional swing device that is disclosed in U.S. Pat. No. 6,626,766. The conventional swing device includes a supporting frame 1, a seat member 3, and a pair of swing arms 2 that are connected to the seat member 3 and that are pivoted to the supporting frame 1 so as to permit swinging of the seat member 3 relative to the supporting frame 1. Two driving units 6 are mounted on the supporting frame 1 for driving the swing arms 2. Each of the driving units 6 includes an axle 51 that is secured to a respective one of the swing arms 2, a swingable member 50 that is coaxially secured to the axle 51 and that is swingable relative to the supporting frame 1, and a driving element 61 that is sleeved rotatably on the axle 51 for driving the swingable member 50 together with the swing arms 2 and the seat member 3 to swing. A pair of studs 522 project from the swingable member 50 toward the driving element 61. The driving element 61 includes a driver-mounting plate 612 that is formed with a slot 62, and a stiff driving rod 65 that is mounted on the driver-mounting plate 612 and that has an inverted U-shaped middle segment 651 and two opposite end segments 652 which extend from two opposite ends of the inverted U-shaped middle segment 651 and which are disposed respectively adjacent to the studs 522 in such a manner that swinging of the driver-mounting plate 612 relative to the axle 51 in a first direction results in pushing of one of the studs 522 by an adjacent one of the end segments 652 of the driving rod 65, thereby resulting in swinging of the swingable member 50 in the first direction, and that swinging of the driver-mounting plate 612 in a second direction opposite to the first direction results in pushing of the other of the studs 522 by the other of the end segments 652 of the driving rod 65, thereby resulting in swinging of the swingable member 50 in the second direction. The driver-mounting plate 612 is coupled to a motor 31 through a gear unit 40. A pushing cylinder 44 is mounted on a worm gear 41 of the gear unit 40, and projects therefrom through the slot 62 in the driver-mounting plate 612 for driving the driver-mounting plate 612 to swing. In operation, the driver-mounting plate 612 is driven by the motor 31 through the gear unit 40 and the pushing cylinder 44 so as to swing back and forth, which, in turn, results in swinging of the swingable member 50.
The conventional swing device is disadvantageous in that the pushing action acting on the studs 522 by the respective end segments 652 of the driving rod 65 is relatively stiff, which can result in a rough swinging movement of the seat member 3.
The entire disclosure of U.S. Pat. No. 6,626,766 is incorporated herein by reference.